JP4903861B2 - Method and apparatus for efficiently transmitting schedule information in a wireless communication system - Google Patents

Abstract

A method in a wireless communication system for reporting buffer information includes selecting a format for a buffer report based on a number of radio bearer groups, k, for which data is available for transmission by a user equipment. The buffer report indicates a respective buffer fill level for one or more radio bearer groups associated with the user equipment. The method also include encoding a buffer fill level for one or more radio bearer groups in a buffer report in accordance with the selected format and transmitting the buffer report.

Description

  The present invention relates to a method and apparatus in a telecommunications system, and more particularly to efficient encoding of buffer status.

  LTE adopts a scheduling mechanism similar to that used for Extended D-Channel Handler (E-DCH) in UTRAN Long Term Evolution (LTE) considerations initiated by the 3rd Generation Partnership Program (3GPP) It is decided that it should be. The scheduler at Node B schedules resources in both downlink and uplink. In the uplink, the scheduler needs information about the data in the buffer of the user equipment (UE). This is achieved by sending a schedule information message from the user equipment to the Node B. Schedule information is transmitted as part of the Media Access Layer Protocol (MAC), so it can be combined with other transmissions (if any are currently in progress) or just to transfer schedule information A MAC PDU can be created and sent alone. The schedule information in E-DCH has the format shown in FIG. HLID is the highest priority logical channel ID, TEBS is the overall E-DCH buffer status, HLBS is the highest priority logical channel buffer status (a value encoded with respect to TEBS, ie a percentage of the reported TEBS value), and UPH Means UE power headroom (this field relates to the power used by the UE), respectively. When the schedule information is received at the Node B, the scheduler determines which logical channel (HLID) has the highest priority, how much data is stored in the UE buffer for this logical channel, and the overall UE buffer. You can know the size (TEBS). This information is encoded into a total of 13 bits.

  In Long Term Evolution (LTE-) systems, there is a desire to adopt finer-grained QoS than is possible with E-DCH. There are some limitations to the E-DCH method. If the user equipment has data on several logical channels (radio bearers), only the amount of data on the channel with the highest priority can be known. However, it is not possible to know whether the remaining data has a slightly higher, lower or very low priority. Furthermore, it is not possible to know how the data is distributed among these priorities. That is, it is difficult to realize service differentiation for services other than those having the highest priority.

  A conventional countermeasure against this problem is to notify the buffer status for each radio bearer (or for each priority / QoS class). In order to achieve a buffer status message with a reasonable size, the number of bits for the buffer size of each radio bearer (or priority / QoS class) is relatively low, eg 2 bits per buffer, as used below. It needs to be small. However, this method implies the problem of providing very low accuracy when approaching the total buffer size of the user device. For example, assuming that there is data for only one radio bearer, the entire UE buffer will be encoded with only 2 bits, which is insufficient. Of course, you can increase the number of bits per buffer, but it increases the size of the buffer status message. One possible option is to encode the total buffer size separately. In this way, the buffer size for each radio bearer could be encoded using a relatively small number of bits (eg 2 bits) and the total buffer size could be encoded using another N bits. . This will allow a rough view of the buffer size for individual radio bearers and a reasonable accuracy for the total buffer size. However, even with this method, the buffer status message will be large.

Typical reasons for having finer accuracy than the E-DCH scheduling method include the following.
1) Resource depletion between QoS levels within the same UE: that resources for low priority data flows can be depleted by higher priority traffic,
2) The operator cannot control the cell capacity division between QoS classes: In E-DCH, the scheduler cannot know which radio bearer has data (except the highest priority radio bearer specified),
3) Free ride of low-priority traffic: If the scheduler does not know how much data is on another radio bearer, when high-priority data is scheduled, the low-priority data can just be carried .
EP 1599 063 relates to an apparatus and method for executing a schedule at a Node B for data transmission of a user equipment UE in a mobile communication system supporting an enhanced uplink dedicated channel (E-DCH). Node B receives schedule assistance information for uplink services to be provided from the UE from a radio network controller (RNC). Node B estimates the amount of data for its uplink service in each schedule period based on schedule support information. Node B schedules data transmission for the uplink service according to the estimated amount of data. As the examiner recognizes, D1 is different from sending a formal report.
US 2004/0224677 relates to a method for selling with buffer occupancy in an uplink schedule for a communication device and includes the following steps. A first step of transmitting buffer occupancy information and a time stamp indicating a communication opportunity last given to the communication device to a plurality of active set base stations. Adjusting the schedule fairness setting for the communication device using the buffer information and the time stamp; Receiving schedule information from the scheduler according to the schedule fairness setting, the next step comprising transmitting according to the schedule information on the uplink channel.

  The purpose of the present invention is to provide a sufficient indication of the amount of data on different radio bearers and a fine-grained total, using as few bits as possible in radio systems such as LTE-systems and high-speed packet access (HSPA) evolution systems. To provide a method and apparatus for realizing efficient encoding of schedule information (buffer status information) that provides UE buffer size.

  Thus, the advantages of the present invention are to provide an efficient method for informing the buffer occupancy level in a wireless system, allowing more information to be provided to the scheduler compared to the latest methods and status reporting. It is possible to realize service differentiation without increasing the overhead.

  Further objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

It is a figure which shows the format of E-DCH schedule information. It is a figure which shows the problem of the method of a prior art. It is a figure which shows the buffer format indicator which concerns on this invention. It is a figure which shows the format about the data on one radio bearer. It is a figure which shows the format about the data on many radio bearers. FIG. 2 is a block diagram of a method according to the present invention. 1 is a block diagram of an apparatus according to the present invention.

  The present invention provides an adaptive buffer status format in which the user equipment selects the most efficient format for instantaneous buffer contents with the help of autonomous or appropriate criteria. If there are several radio bearers, the buffer occupancy level encoding reduces the number of bits required to encode the total UE buffer size information, so information from the buffers on the individual radio bearers Is used.

  The present invention generally relates to a method for efficiently communicating schedule information processed in one unit of a wireless system in a wireless communication system. The method includes adaptively selecting (610) a buffer status format 615 for indicating the buffer occupancy level of the scheduler and encoding (620) the buffer occupancy level. The encoding step is intended to reduce 625 the number of bits required to encode the total buffer size information.

  The first embodiment of the present invention relates to an adaptive buffer status format. An efficient buffer status type report for use based on how many radio bearers are configured, which services are being used, etc., as well as the instantaneous buffer occupancy levels on individual radio bearers Format. Thus, the user equipment selects (eg autonomously) the format of the buffer status report so as to minimize the number of bits required (or maximize the information that can be extracted using a fixed number of bits). Need to be allowed. The basic structure of the buffer status report is shown in FIG. A buffer type indicator field 31 (eg, 1 or 2 bits long) is used to indicate the format in which the remaining buffer report field 32 is encoded.

  Later, some examples of the buffer report format will be described. In these examples, a total number of bits of 12 has been selected, which is merely intended to illustrate the possible relationship of field sizes in various formats. However, since the receiver of the buffer status report can estimate the format length from the buffer format indicator, different formats can actually have different lengths.

  When data exists only on one radio bearer, the radio bearer id (RBid) (for example, 3 bits long) is set in the field 41, and the buffer occupation level is set in the field 42 (for example 9 bits long). It is efficient to show. This is shown in FIG. It is expected that the case where data exists only on one radio bearer should be common. This format provides a very high accuracy of the total buffer size in such a general case.

In order to provide service differentiation, it is necessary to convey information about the amount of data for each QoS class, traffic priority or similar criteria for different radio bearers or groups of radio bearers. For simplicity, the expression radio bearer is used below. In the example shown in FIG. 5, four radio bearers are set. The buffer occupancy level B (denoted as Bk) for the set radio bearer k is encoded in N-bit fields 51, 52, 53, and 54. For example, each value of 2 ^N that Bk can take is mapped to one section having a buffer occupation level, such that Bk = 01 means a buffer occupation level of 100 to 500 bytes. The mapping between Bk and buffer occupancy level interval is probably defined by the specification, but may be configurable by higher layer signaling.

  When encoding the total UE buffer B denoted as Btot into the field 55, the fields B1. . . Using the information extracted from B4, the accuracy of the information is improved as follows. B_estimaged = B1 + B2 + B3 + B4 and so on. . . By combining B4, a sufficient estimate of the total UE buffer occupancy level can be obtained. This estimation error Err = B-B_estimated is encoded in the field Btot. Since the range of Err values is much smaller than the range of B values, the accuracy of Btot can be improved by this method. It can be seen that this format gives a rough indication as to the buffer occupancy level on individual radio bearers, with moderate accuracy of the total UE buffer occupancy level.

  One of the other encoding methods when there are several radio bearers is to first encode the UE buffer total size Btot in one field and then set the buffer occupancy level Bk for each radio bearer in Btot Encoding is performed as a ratio of the indicated value. The advantage compared to having Bk and Btot indicate the absolute buffer occupancy level is that the range of Btot values is smaller than the range of possible buffer occupancy level values.

  There are several ways for the user equipment to select the buffer status type. One conceivable is that the format can be set via a higher layer signaling protocol (eg RRC) so that the user equipment always uses the same format. This format can then be reset, for example depending on the number of services to be set. According to another possible method, the user equipment can autonomously select the format to use. This selection can be based, for example, on the buffer occupancy level of individual radio bearers. For example, if there is data on only one radio bearer, a certain format is selected, while in other cases, i.e., if there are several radio bearers, another format is selected. Finally, the user equipment can use several formats. As a result, not only the total buffer occupancy level but also the information about the data on the individual radio bearers is highly accurate.

  The following example gives five configured radio bearers. RRC signaling, SIP, VoIP, video, best effort (BE) Internet access. In this example, a multimedia telephony service is configured using service components of SIP signaling, VoIP and video. A radio bearer is set in addition to RRC signaling, and a best effort bearer is used for Internet access. A mapping example of QoS indicators and priorities is shown in the following table (in practice, the priorities would be a list of radio bearer IDs). The QoS indicator and priority mapping will be set to the UE via RRC signaling.

Table 1

  In a typical case, the scheduler will use QoS indicator 1 to indicate that the radio bearer should be scheduled with default priority. For example, if a resource starvation occurs for a BE Internet access bearer, it will be detected by the Node B scheduler and will be scheduled for some time with a QoS indicator 2 that increases the priority of the BE. Similarly, QoS indicator 3 or 4 would be used when a radio bearer carrying VoIP or video requires more resources than allowed by default priority. The bottom row of the table does not include BE Internet access, which implies that data from this radio bearer is not allowed to be transmitted. As can be seen from the table, in this example, RRC signaling always has the highest priority. It is a possible implementation, but it goes without saying that RRC priority may be lowered.

  FIG. 7 shows an exemplary apparatus 700 (eg, in a UE) according to the present invention. The apparatus 700 includes a scheduler 710 that schedules information being processed in one or more buffers 720. The apparatus further includes a processor 730 that adaptively selects a buffer status format to indicate the scheduler buffer occupancy level, and a buffer occupancy level to reduce the number of bits required to encode the total buffer size information. And an encoder 740 for encoding. The device further includes a transmitter 750 that transmits information elements including buffer status reports to other network devices. The apparatus has been described very simply, including the functional parts essential for the implementation of the present invention.

Claims (14)

A method in the wireless communication system for efficiently transmitting schedule information processed in a user apparatus of a wireless communication system, comprising:
A buffer status format for indicating the buffer occupancy level of the user equipment, at least a first type and from the second form, a plurality of radio bearers or more radio bearers group data is present for transmission ( k) adaptively selecting based on (610);
For each radio bearer or radio bearer group (k), the buffer occupancy level (B _k) possess a step (620) for encoding the N bit field,
The first format indicates a buffer occupancy level for one radio bearer or a radio bearer group, the second format indicates a buffer occupancy level for a plurality of different radio bearers or a plurality of bearer groups,
How each of the values of 2 ^N that can be taken for the B _k are mapped to a buffer fill level interval and said Rukoto.   The method of claim 1, wherein the encoded buffer occupancy level is included in a buffer status report. The method of claim 1, wherein the selection of the buffer status type is performed autonomously by the user equipment. The method of claim 1, wherein the buffer status type selection is set via higher layer signaling. The method of claim 1, wherein the selection of the buffer status type is further performed by applying a predetermined criterion.   6. The method of claim 5, wherein the criterion is an instantaneous buffer occupancy level of each of a plurality of radio bearers.   6. The method of claim 5, wherein the criterion is the number of configured radio bearers.   6. The method of claim 5, wherein the criteria is an applied service. The data exists on one radio bearer, and the step of selecting the buffer status format includes the step of selecting the first format, and the first format includes identification information of the radio bearer, a buffer occupation level, The method of claim 1 comprising: The data is present on a plurality of radio bearers, and the step of selecting the buffer status format comprises the step of selecting the second format, wherein the second format is a buffer occupancy level of each of the plurality of radio bearers. The method of claim 1 including encoded information of the total buffer size.   The method according to claim 10, characterized in that the buffer occupancy level information for each radio bearer is encoded as a percentage of the total buffer size. A equipment for communication have you to radio communications system,
A buffer status format for indicating the buffer occupancy level of the device, at least a first type and from the second form, a plurality of radio bearers or more radio bearers group data is present for transmission ( k) processing means configured to adaptively select based on
An encoder configured to encode a buffer occupancy level (B _k ) into an N-bit field for each radio bearer or radio bearer group (k) ;
Have a, a transmitter configured to wirelessly transmit laden buffer status report the encoded bit fields,
The first format indicates a buffer occupancy level for one radio bearer or a radio bearer group, the second format indicates a buffer occupancy level for a plurality of different radio bearers or a plurality of bearer groups,
The value of each of 2 ^N that can be taken for the B _k is mapped to a buffer fill level interval and wherein the Rukoto. The processing means is configured to select the first format when data is present on one radio bearer, and the first format includes identification information of the radio bearer and a buffer occupancy level. The apparatus of claim 12. The processing means is configured to select the second format when data is present on a plurality of radio bearers, and the second format is a buffer occupancy level and a total buffer of each of the radio bearers. claim 1 2 Symbol mounting apparatus which comprises a coded information size.

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